J. Planar Chromatogr. 31, 213-219 (2018). HPTLC of β-sitosterol in the leaves of five Ficus species (F. carica, F. nitida, F. ingens, F. palmata, and F. vasta) on silica gel with ethyl – acetate 4:1. Detection by spraying with p-anisaldehyde reagent followed by drying. Quantitative determination by absorbance measurement at 550 nm. The hRf value for β-sitosterol was 17. Linearity was in the range of 100-1400 ng/zone. The intermediate precision was below 2 % (n=6). The LOD and LOQ were 32 and 98 ng/zone, respectively. Recovery was between 98.5 and 99.7 %.

J. Planar Chromatogr. 31, 169-172 (2018). HPTLC for the analysis of enzyme activity of the purified β-glucosidase from Cyamopsis tetragonoloba with natural isoflavonoid (genistin and daidzin) and flavonoid O-glycoside (rutin, naringin and hesperidin) substrates on silica gel with toluene – ethyl acetate – acetone – formic acid 20:4:2:1 for genistin, daidzin and rutin, methanol – chloroform 3:17 for hesperidin and methanol – ethyl acetate 3:7 for naringin. Detection under UV 254 nm. The hRF values were 18 and 32 for daidzein and genistein, respectively. TLC was successfully used as the first step for validation of the metabolic product formation.

CBS 120, 14-15 (2018). The drugs cefixime trihydrate (CEFI) and azithromycin dihydrate (AZI) were subjected to hydrolytic degradation (with water, 0.5 N HCl or 0.5 N NaOH), oxidative degradation (with 3 % and 30 % hydrogen peroxide), thermal degradation (heated at 100 °C and 200 °C for 1 h and 2 h) and photolytic degradation (exposed to fluorescent cold white light and UV light). HPTLC of CEFI, AZI, and the degradation samples on silica gel with ethyl acetate – methanol – acetone –_x000D_ toluene – ammonia 2:10:14:1:1 to the migration distance of 80 mm. Detection of AZI by immersion into sulfuric acid reagent (1:4 in ethanol) and heating at 100 °C for 5 min. Evaluation under UV 254 nm, UV 366 nm, and white light. Quantitative determination by absorbance measurement at 235 nm for CEFI and 530 nm for AZI. Linearity was in the range of 500–2500 ng/zone for CEFI and 50–250 ng/zone for AZI. The LOD and LOQ (ng/zone) for CEFI were 58 and 175, respectively, and for AZI 3 and 10, respectively. Precision (%RSD) was <2 %. In the forced degradation studies, CEFI degraded to 4 major products under different stress conditions. AZI showed only one additional peak upon acid and neutral hydrolysis.

J. Planar Chromatogr. 31, 497-504 (2018). HPTLC of chloroacetamide derivatives on RP-18 with ethanol and tetrahydrofuran as organic modifiers with water. Lipophilicity was examined by cluster analysis and principal component analysis. The obtained chromatographic parameters of the examined acetamides were correlated with the standard measure of lipophilicity, log P.

and their herbal formulations. J. Planar Chromatogr. 31, 451-459 (2018). HPTLC of berberine chloride (1) and galangin (2) in Tinospora cordifolia M._x000D_ and Alpinia galanga on silica gel with toluene ‒ ethyl acetate ‒ formic acid 3:6:1. Quantitative determination by absorbance measurement at 267 nm. The hRF values for (1) and (2) were 17 and 82. Linearity was between 200 and 1200 ng/zone. LOD and LOQ were 28 and 86 ng/zone for (1) and 2 and 5 ng/zone for (2), respectively. The intermediate precision was <2 % (n=3). Recovery was between 97.5 and 102.6 % for (1) and (2).

J. Planar Chromatogr. 31, 367-376 (2018). HPTLC of folic acid (1) in the presence of its impurities pteroic acid (2) and para-amino benzoic acid (3) on silica gel with methanol – iso-propanol – water – glacial acetic acid 90:5:5:2. Quantitative determination by absorbance measurement at 280 nm. Linearity ranged between 0.4-4 μg/zone for (1), 0.1-1.5 μg/zone for (2) and 0.2-1.8 μg/zone for (3). LOD and LOQ were 132 and 398 ng/zone for (1), 33 and 99 ng/zone for (2) and 66 and 199 ng/zone for (3), respectively. The intermediate precision was <2 % (n=3). Average recovery was 100.0 % for (1), 98.6 % for (2) and 100.7 % for (3). Results obtained by the HPTLC method showed no significant difference when compared with those obtained by applying the reported RP-HPLC method.

J. Planar Chromatogr. 31, 272-279 (2018). HPTLC of chlorpheniramine (1), pseudoephedrine (2), and ibuprofen (3) on silica gel with ethyl acetate ‒ methanol ‒ ammonia 20:5:2. Quantitative determination by absorbance measurement at 262 nm. The hRF values for (1) to (3) were 78, 64 and 29, respectively. Linearity was between 0.2 and 9 μg/zone for (1), 2 and 30 μg/zone for (2), and 5 and 50 μg/zone for (3). LOD and LOQ were 72 and 218 ng/zone for (1), 285 and 864 ng/zone for (2), and 1004 and 3042 ng/zone for (3), respectively. The intermediate precision was <2 % (n=3). Average recovery was 100.5 % for (1), 100.9 % for (2) and 100.7 % for (3).

J. Chromatogr. 299, 513-515 (1984). TLC and HPTLC of PTH derivatives of amino acids on silica containing a fluorescence indicator with ethanol - acetic acid 7:3. Detection by UV 366 nm. New and highly sensitive method for the detection of PTH-histidine (detection limit 60 pmol).